Drying apparatus.



Patented Dec. 2. I902.

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F. V. L. HIORTH.

DRYING APPARATUS.

(Application filed Sept. 5, 1901.)

(No Model.)

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No. 715,070. Patented Dec. 2, I902.

F. V. L. HIORTH.

DRYING APPARATUS.

(Application flied Sept. 5, 1901.)

2 Sheets-Sheet 2.

(Ila Model.)

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UNTTED STATES PATnNT OFFIcE.

FREDRIK VILHELM LOUIS I'IIORTH, OF CHRISTIANIA, NORWAY.

DRYING APPARATUS.

SPECIFICATION forming part of Letters Patent N 0. 715,070, dated December 2, 1902. Application filed deptemher 5, 1901. Serial No.74,573. (No model.)

To all whont it may concern:

Be it known that I, FREDRIK VILHELM LoUIs HIORTH, a subject of the King of Sweden and Norway, residing at Christiania,Norway, have invented certain new and useful Improvements in Drying Apparatus; and I do hereby declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

My invention relates to means for drying materials, especially such materials as pulp, pasteboard, yarn, and other flbl'OllS products.

In the systems generally used for drying pasteboard or the like it is customary to transport the material to be dried through appropriate channels and admit therein more or less heated air, such hot air being, according to a prior patent, caused to flow through said drying-channels in the same direction as the materials in order to prevent fully dry hot air from coming into contact with already dried material, whereby the latter, in case of pasteboard or the like, would be liable to deterioration, since it would become too dry.

According to my subsequent experiments, which have led to the present invention, I have found it preferable to modify the operation of the apparatus so as to carry out the drying process without or nearly without any supply of fresh air to the apparatus, the drying effect being in this way due to superheated steam or vapor rather than to hot air.

The object of my presentinvention is, primarily, possibly the best utilization of heat, and, secondly, to provide against any detrimental action of the heat upon the material to be dried, the fibers being, in fact, by the presence of the vapors enabled to retain their flexibility unimpaired even when heated to high degrees of temperature. When carried out in this way, the drying process will also require less time, because the fibers cannot, previous to being fully dried in the interior of the sheets, obtain a surface crust or scale by the action of dry air, whereby the pores would be clogged and further progress of the drying process retarded or prevented.

In carrying out my present invention I preferably make use of a hot air furnace and a fan, by which means one and the same quantity of air is reheated over and over again and kept in constant circulation through the drying-channels, fresh air being admitted into the circulation only in such quantities as required to compensate for the quantity of air which is led away in order to carry off the vaporized water. As this mode of operation allows of raising the temperature to very high degrees, a small quantity of air will suffice for carrying away this vaporized water, whereby also the heat contained in this air and vapor mixture may be recovered by leading the supply of fresh air through a plurality of thin tubes arranged (like an economizer) in the exhaust-channel, an arrangement which cannot be realized profitably unless the amount of heat contained in the escaping air is large relative to the volume of the air.

Figure 1 is a vertical sectional elevation of said apparatus. Fig. 2 is a similar view of the lower part of said apparatus on a plane at right angles to that of Fig. 1; and Fig. 3 is a sectional plan on the line A B of Fig. 1 with the gratings in chambers a, b, and 0 removed.

The device for conveying the material to be dried through the drying-channels is indicated in dotted lines in Fig. 1. This conveyer, however, need not be specifically described, as it may be of any construction and forms no part of this invention. The tower-- like construction has two drying-channels a and b and an intermediate heating-channel c c, in which the furnace or air-heater d is placed. The arrangement of this furnace, which is preferably provided with ribbed heating tubes or radiators, as well as its communication with the fire-chamber e and chimney f, will be readily understood byreference to Fig. 2. This construction is well known and forms in itself no part of my invention. The heated air escapes above the furnace in part through the top opening g, which is covered by a grate, a small part also escaping through the lateral openings it into the drying-channels. Mounted at the base of the channel I) is the aspirator or fan t', which serves to draw the moist air and drive it in part through the passage 7 into the channel at and in part through the opening 70 into the heating-channel c. The air passing into the channel a ascends in part throughout the whole length of this channel, while another part escapes through an aperture Z, leading into the exhaust-channel m. The thin tubes n (shown in section) in this channel connect the inletchannel 10 for fresh air (see Fig. 3) with a channel 0, provided on the opposite side of the channel m, in which channel the air thus preheated passes downwardly to the bottom of the apparatus, where channels 4" and q are provided for leading the air to the outlets s and 25, opening into the channel a.

The vapors condensing in the heater 1% may be recovered and utilized as feed-water for the boiler. Adjustable valves 0 are provided in convenient places in order to allow of regulating the air-draft or of completely intercepting the air-supply (automatically, if desired) in case the materials should take fire within the apparatus.

I claim 1; In a drying apparatus, the combination, with two dryingchannels communicating with.each other at their ends, of an intermediate air-heating channel communicating at each end With thedrying-channels'and also communicating with a fresh-air channel, and means for causing the circulation of the air therethrough.

2. In a drying apparatus, the combination with two vertical drying-channels communieating at both ends with each other, of an intermediate air-heating channel communicating at the bottom with the drying-channel and with a fresh-air channel and at the top and through openings in the side walls with the drying-channels.

3. A drying apparatus comprising two drying-channels communicating with each other at their ends, a channel interposed between the drying-channels and communicating with the latter, an air-heater in the intermediate channel, a fan or suction apparatus, an inletopening for fresh air, an outlet-opening for moist air, means for regulating the flow of the air, a door opening to each drying-channel, and a carrier for conveying the materials to be driedthrough the drying-channel in the same direction as the flow of the air.

4. In a drying apparatus, the combination with a continuous endless drying-channel, an

interposed air-heating channel, means for circulating air through the drying-channel and the air-heating channel, an inlet for fresh air opening into the air-heating channel, and an outlet for moist air, of means for utilizing the heat contained in the escaping moist air for preheating the fresh air which is introduced into the air-heating chamber.

5. In a drying apparatus, the combination with a continuous endless drying-channel, and an interposed air-heating channel, of means for circulating the air through the drying-channel and the air-heating channel, an outlet for moist air, fresh-air-inlet tubes located in the air-outlet channel in such a manner as to be heated thereby, an inlet for fresh air communicating with said tubes, and a passage leading from said air-tubes and communicating with the air-heating channel.

6. An apparatus for drying materials comprising essentially two drying-channels communicating with each other at both ends, a channel interposed between the drying-channels and communicating with the latter attheir ends, an air-heater in the intermediate channel, a fan or suction apparatus in one of the drying-channels, an inlet-opening for fresh air at one end of the intermediate channel, and an outlet-opening for moist air in one of the drying-channels, means for regulating the flow of air through the several openings, and a doorway in each drying-channel, and a carrier for conveying the materials to be dried through the drying-channels from one doorway to the other in the same direction as the flow of the air.

7. Ina drying apparatus, the combination with a continuous endless channel, of an interposed air-heating channel, means for circulating the air through the drying-channel and the air-heating channel, an inlet for fresh air opening into the air-heatingchannel,doors for introducing and removing the material to be heated, an outlet for moist air from the drying-channel, and means for utilizing the heat contained in the escaping moist air for initially heating the fresh air prior to its introduction to the air-heating chamber.

In witness whereof I have hereunto set my hand in presence of two witnesses.

FREDRIK VILHELM LOUIS HIORTH.

Witnesses:

J. G. THAIRLON, HANS J ORGENSEN. 

